Lamp or plug and receptacle therefor



E. R. EVANS LAMP 0R PLUG AND RECEPTACLE THEREFOR Nom 21, 1939.

Filed March 10, 1957 Patented Nov. 21, 1939 UNITED srnrss LAMP on PLUGAND asoarraons rnennroa Earl R. Evans, Jackson Heights, N. Y.Application March. l0, 1937,Serial No. 130,178

3 Claims.

This invention relates to electric lamps and sockets or receptaclestherefor, or in general to electric connectors of the plug and sockettype.

An object of the invention is to provide a shockproof or safety socketand an improved lamp base or plug adapted to be readily inserted intosaid socket, the lamp base or plug and the socket being as simple andrugged in construction as the ordinary Edison screw plug or lamp baseand socket. By shockproof is meant a socket in which the possibility ofaccidental shock from exposed live contacts when the lamp or plug isremoved from the socket or receptacle, or from touching the contacts ofthe plug or lamp as it is inserted in or removed from the socket, isobviated or materially reduced.

Prior sockets or receptacles of this character have been oi acomplicated construction or have not come into general use becai cfethey required a specially constructed plug or lamp base which could notbe used'in connection with the standard sockets or receptacles alreadyin general use to such a large extent that it would be impracticable toreplace them. Li accordance with a further feature of the invention, thelamp base or plug of the connector embodying the .invention althoughincdiiied from the usual construction as required by the construction ofthe iinproved socket is also adapted for insertion in the ordinarySocket wherever the latter are alread installed.

Another object of the-invention is to provide lamp with a wedge-shapedcontact of novel character.

Another object of the invention is to provide a socket or receptaclewith movable insulating members adapted to be displaced by the:wedgeshaped contact of the cooperating lamp or plug.

A still further object of the invention is to provide, in a socket ofthe character described, a novel contact device or switch for connectinga contact or contacts of the socket to the supply conductors when thelamp or plug is inserted in the socket.

Other objects and advantages of the invention will be apparent from thefollowing description oi thepreierred embodiments thereof shown on theaccompanying drawing, wherein Fig. l is a longitudinal sectional View ofa lamp base and socket or receptacle constructed in accordance with theinvention;

Fig. 2 is a cross-section taken on the line 2 2 of Fig. 1;

Fig. 3 is a similar view taken on the line 3--3 of Fig. l;

. tached shell contact while obviating distortionof spring 22, a springformed of a helix coiled into (o1. 17e-ass) Fig. 4 is a sectional detailtaken on the line :iof Fig. 1; and Fig. 5 is a view similarto Fig. l ofya modified form of socket or receptacle, with the base of the lamppartly inserted in the socket.

Referring to Fig. 1 of the drawing, in accordance with the invention thelamp (or plug) I0 forming one element of the connector is provided withthe conventional threaded shell contact il which in the case of a lampis cemented to the lamp bulb in the usual manner, the end oi said shellcontact being closed by a molded insert l2 carrying the center or tip`Contact i3. The contact I3 is shown as soldered at lf3 Vto one of thelamp terminal conductors it, the other of said conductors beingconnected to the shell contact Il.

Instead of the ordinary flat center contact, the contact i 3 projectsfrom the-body of the lamp,- base and is preferably conicalor'wedge-.Jhaped for a purpose to be described. As shown, the insert i2which maybe of glass has a corresponding conical portion engaging andsupporting' the contactmember i3, and capable of transmittingsubstantial inward Contact pressure to the at-v 5 the tip Contact. Ifdesired, the contact member i3 may be shortened so that it does notcover all or any substantial part of the projecting portion of theinsert i2, and the size, shape and arrangenient` of these parts of thebase may be otherwise varied somewhat if the functions thereof .apointed out hereinafter be borne in mind. The socket or receptacleforming the second'element of the connector comprises a casing orhous-3- ing vi8 of any suitable character, preferably a one-piece moldedshell of Bakelite, Textolite or bre, contact members i9 and 2@ adaptedto cooperate with the contacts l l and i3 of the lamp base or plug, andmovable or vseparable co-planar insulating members 2i arranged to shieldthe contact member 2i) from accidental contact with the fingers or ascrew-driver, pencil or the like when the lamp or plug is removed fromthesocket. In this modification of the invention, Ythe contact memberVi9 is intendedvtobe connected to the grounded side of the supply circuitso that there is no danger of shock or short-circuit al-v though it isexposed.

The insulating members 2l are made of any suitable insulating materialand, in the preferred form of the invention, comprise two truncatedparts engaging at the center of 'the socket andy held together byresilient means, ,such as a Wire circular shape With its ends fastenedtogether or any equivalent means. Ihe two insulating members 2| areretained in the socket, as by the grooved end portion of an insulatingblock 23, the members being slidable in said block. The block 23 is alsogrooved to receive the spring 22 as shown in Figs. 3 and 4, and is soconstructed as to prevent contact of the spring with the center contactmember 20 in case the spring breaks after extended use and also toaccurately center the members 2I t loosely in the transverse groove inthe block 23 and, as clearly shown in Fig. 4, the tapered sides 24 ofsaid members are at a greater angle with the base surface thereof thanthe sides of the groove in the block 23 in order to obviate wedging orbinding of the same in said groove. As shown in Figs. 3 and 4, thegroove in the members 2| or the block 23 is preferably discontinuous toprevent the spring 22 from turning in the groove.

The contact 253 is disposed in a central aperture in the insulatingblock 23 and opposite said contact, the ends of the insulating members2l are cut away to form a tapered cavity 25 adapted to receive the endof the Wedge-shaped tip contact I3 of the lamp base whereby the shieldmembers 2l will be spread apart as the lamp is inserted in the socket toexpose the Contact member 23 (see Fig. 5). Thus the live contact of thesocket is shielded when the lamp is removed from the socket but the lampmay be inserted in the socket and turned until contact is made with thetip of the lamp in the usual manner. While the specic form and mountingof the insulating members 2l shown have been chosen merely to illustratea suitable construction which may be altered without departing from thescope of the invention, this construction has the advantages ofruggedness, durability and simplicity. In addition, it will be notedthat in the event the spring 22 breaks, the socket will function as anordinary unprotected socket.

The elements of the socket may be mounted in the casing I8 in anydesired manner. As shown, the end of the contact member I9 is spun overthe block 23 and also secured thereto by the terminal screw 29 extendingthrough the shell contact into the block 23. The body portion ofl thecasing I8 may be provided with internal ribs 3B (see Fig. 2) cooperatingwith the head of the screw 29 to prevent the shell from turning in thehousing. The center contact 20 is preferably a round pin or stud urgedtoward the open end of the socket by a spring 3l and having its outerend drilled and tapped to receive the second terminal screw 32. There isthus, no possibility of a loose or high resistance joint between theterminal and the contact face, and since the spring 3l does not carryany current its resiliency will remain constant. The outer end of thecontact member 2|] may be of substantially square cross-section, asshown in Fig. 2, so that it cannot turn in the supporting member 23. Theblock 23 with the elements of the socket carried thereby may beWithdrawn through the mouth of the casing I8 in order to attach thesupply conductors 33 to the terminals 32 and 29. If desired, means maybe provided to lock the member 23 in the casing or the casing may bemade of two interlocked sections according to usual practice.

If desired, the socket embodying the invention may be constructed tocomplete the circuit to the shell contact I9 upon the insertion of thelamp or plug in the socket so that accidental shock is avoided in theevent that the shell terminal is not connected to the grounded side ofthe supply circuit. 'Ihis modification of the invention is shown in Fig.5, which illustrates a construction similar to that shown in Figs. 1-4except that the center contact member 23a, corresponding to the member20 of Fig. 1, carries an insulating disc 35 supporting a circularcontact ring 36 adapted to engage the end of the shell contact memberI9a when the center contact member 23a is moved by engagement with thetip contact I3 of the lamp as it is inserted in the socket. The supplyconductors 33 are connected to the terminals 32 and 31, the latter ofwhich is connected to the contact ring 36. Thus the contact member 2Gois shielded and the contact member I9a is disconnected from the supplycircuit until the lamp is inserted in the socket and turned until itfirmly engages the contact member 2a. If desired, the contact ring 36may be mounted on the block 28, corresponding to the block 23, and thecontact shell lila may be movable to effect contact therewith as thelamp presses against the contact 20a. Various other modifications willoccur to those skilled in the art and may be made without departing fromthe scope of the invention as dened in the appended claims.

I claim:

1. A connector having threaded plug and socket elements, said plugcomprising a wedge-shaped center contact member projecting from the bodyportion of the plug and of substantial length, a contact member in saidsocket adapted to be engaged by said Erst-mentioned contact member andslidably mounted insulating elements covering said socket Contact memberand constructed and arranged to be moved by the projecting wedge-shapedcontact member of the plug to permit engagement thereof with said socketcontact member as the elements of the connector are threaded together.

2. In a socket or receptacle, a center contact member, a groovedsupporting member embracing the same, two insulating members disposed inthe groove in said supporting member and movable to expose said contactmember and resilient means engaging said insulating members to positionthe same with the inner ends thereof adja- Cent said contact memberuntil spread apart to expose the latter.

3. In a socket or receptacle, a center Contact member, separableco-planar insulating members shielding the contact surface of saidcontact meinber and mounted for transverse opposed movement in saidsocket or receptacle, and resilient means engaging said insulatingmembers and tending to hold them together.

EARL R. EVANS.

